Clinical and Epidemiologic Patterns of Chikungunya Virus Infection and Coincident Arboviral Disease in a School Cohort in Haiti, 2014-2015.

BACKGROUND: Beginning in December 2013, an epidemic of chikungunya virus (CHIKV) infection spread across the Caribbean and into virtually all countries in the Western hemisphere, with >2.4 million cases reported through the end of 2017. METHODS: We monitored a cohort of school children in rural Haiti from May 2014, through February 2015, for occurrence of acute undifferentiated febrile illness, with clinical and laboratory data available for 252 illness episodes. RESULTS: Our findings document passage of the major CHIKV epidemic between May and July 2014, with 82 laboratory-confirmed cases. Subsequent peaks of febrile illness were found to incorporate smaller outbreaks of dengue virus serotypes 1 and 4 and Zika virus, with identification of additional infections with Mayaro virus, enterovirus D68, and coronavirus NL63. CHIKV and dengue virus serotype 1 infections were more common in older children, with a complaint of arthralgia serving as a significant predictor for infection with CHIKV (odds ratio, 16.2; 95% confidence interval, 8.0-34.4; positive predictive value, 66%; negative predictive value, 80%). CONCLUSIONS: Viral/arboviral infections were characterized by a pattern of recurrent outbreaks and case clusters, with the CHIKV epidemic representing just one of several arboviral agents moving through the population. Although clinical presentations of these agents are similar, arthralgias are highly suggestive of CHIKV infection.

Spatial distribution of Zika virus infection in Northeastern Colombia.

In this study, we investigated the weekly reported spatio-temporal distribution and topographic risk factors for Zika virus (ZIKV) infection in northeastern Colombia. Weekly reported surveillance data, including clinical, suspected and confirmed cases from the ongoing ZIKV epidemic in the Santander and Norte de Santander departments (Santanderes) in Colombia were used to estimate cumulative incidence rates. Spatial analysis was performed to develop hot spot maps and to identify spatial topographic risk factors for infection. From January 1, 2016 to March 19, 2016, 11,515 cases of ZIKV were reported in Santanderes, with cumulative rates of 316.07 cases/100,000 population for the region (representing 18.5% of the cases of the country). Five municipalities (four in Norte de Santander) reported high incidence of ZIKV infection (>1,000 cases/100,000 pop); these municipalities are close to the border with Venezuela. Most of the cases reported occurred mainly in low altitude areas, and persistent hot spots were observed. Higher infection rates were reported in the Northeastern part of the study area. Use of risk maps can help guide decisions for the prevention and control of ZIKV. Hotspots on the Colombia-Venezuela border can have implications for international spread.

Clinical and spatial features of Zika virus in Mexico.

BACKGROUND: Zika virus (ZIKV) is an emerging arbovirus transmitted to humans by Aedes mosquitoes, the same vectors that transmit dengue virus and chikungunya. Recent work has suggested that prior infection with dengue could lead to more severe clinical disease in ZIKV patients. Here, we describe the spatial distribution of and clinical symptoms experienced by ZIKV cases in Mexico. METHODS: We performed Fisher's Exact test and Pearson's Chi-Square tests on data from Mexico's national surveillance system on the demographic and clinical characteristics of ZIKV patients (N=84), and then a multivariate logistic regression analysis to determine demographic risk factors for patients presenting with at least 9 symptoms. We also mapped the cases to describe the spatial distribution of ZIKV in Mexico. RESULTS: Results from the multivariate logistic regression analysis indicate that, controlling for all covariates, sex (male) is a significant protective factor in reporting a high number of symptoms (OR=0.36, 95% CI: 0.14, 0.92), and that a one-year increase in age is associated with a 4% increase in odds of having at least 9 symptoms (95% CI: 1.00, 1.08). Spatial analysis revealed more than 50% cases reported within 50km of railways. CONCLUSION: We found that sex and age are both significant risk factors for ZIKV infection severity, using number of reported symptoms as a proxy. The presence of cases along railways indicates that transportation networks within Mexico may be relevant for the national and international spread of the disease.